1. Field of the Invention
The present invention relates to improvements in lamp dimmers of the type adapted to be connected in-line with a conventional power cord used to connect an electric lamp or the like to a power source.
2. Description of the Prior Art
In the commonly assigned U.S. Pat. No. 4,104,606, issued in the name of R.R. DeWitt, there is disclosed a lamp dimmer switch which is connectable in-line with a conventional power cord in order to selectively vary the power applied to an electric lamp and thereby adjust or dim the lamp's luminous output. Such dimmer switch includes a plastic (electrically insulating) housing containing a dimming circuit and a movably mounted dimming actuator which, when moved, varies the output of the dimming circuit as a function of the actuator's position. In order to connect the dimmer switch in line with the lamp's power cord, it is first necessary to sever the power cord at some point intermediate the lamp and plug. Having severed the cord, each of the two severed ends of the cord is inserted into an opening formed in the plastic housing and designed to receive a severed cord end. Upon being inserted a predetermined distance into such opening, each of the severed ends of the power cord is positioned to be acted upon by a plunger member which is also movably mounted on the dimmer housing. Movement of the plunger member in a direction perpendicular to the power cord acts to deflect the severed end of the power cord into engagement with a pair of conductive "stab" terminals, each being electrically connected to one of the input or output terminals of the dimming circuit. During movement of the plunger members, the stab terminals are designed to pierce the power cord's insulation and thereby make electrical contact with the internal conductors of the power cord.
In the dimmer switch described above, the combination of stab terminals and plungers have proven highly reliable in connecting a power cord to a dimming circuit without any need for stripping insulation from the cord, dissembling the housing to expose circuit terminals, and the other difficulties normally associated with making electrical connections to a device of this type. The reliability of the circuit connection, however, has been achieved by carefully sizing the overall dimensions of the power cord openings in the switch housing to receive a power cord of a particular width, such as the width of SPT-1 cord, and by carefully locating the stab terminals along the path of deflection taken by the power cord ends when acted upon by the plunger. If one were to attempt to connect the dimmer switch in line with a power cord of wider or narrower dimensions than that for which the switch housing was designed, one would find that the wider cord would not fit within the housing's power cord opening, and that the narrower cord would not be reliably located by the walls of the opening to achieve a reliable connection between the stab terminals and the cord conductors. Thus, to assure a reliable in-line connection, a different dimmer switch housing is required for each power cord size.